B. THE TOXIC DISEASES.
' ONE of the most exquisitely toxic bacteria of which
we have any knowledge is the bacillus discovered in
1884 by Nicolaier, obtained in pure culture by Kitasato
in 1889, an(l now universally recognized as the cause of
tetanus. It is a peculiar organism, whose striking feature
is a considerable enlargement of one end, in which a
bright round spore is seen (Fig. 72). The bacilli which
FlG. 72.—Bacillus tetani; x 1000 (Frankel and Pfeiffer).
are not sporiferous, are long, rather slender, have rounded
ends, seldom unite in chains or pairs, are motile, and
have no flagella. The bacilli stain readily with ordi-
nary aqueous solution of the anilin dyes, and also very
readily by Gram's method.
The tetanus bacillus is a common saprophytic organ-
ism which can be found in most garden-earth, in dust,